Pantograph



E. w. sToNE May 18, 1937.

ATTORNEY May 1 8, 1937. E. w. STONE y 2,080,971

PANTOGRAPH Filed July 28, .[936 3 Sheets-Sheet 2 INVENTOR BY www.;

ATTORNEY May 18, 1937. E. w. s'roNE '2,080,974

PANTOGRAPH Fi1ed Ju1y 2a, 1956 s sheets-'sheet 3 /NVENTOR.'

EAN@ m. mw@ l Bf .ATTORNEY Patented May 18, 1937 Y l *Y 'Y y UNITEDSTATES TENT GFFICE PANTOGRAPH Edwin W. Stone, Longmeadow, Mass.,assigner to Bigelow-Sanford Carpet C0. Inc., Thompsonville, Conn., acorporation of Massachusetts Application July 28, 1936, Serial No.93,000

7 Claims. (Cl. 33-21) This invention relates to pantographs of the tonoutline of a common type of pantograph aptype employed for transcribinga design from a paratus, but with my compensating apparatus inpatternpresenting a plane surface, to an object corporated therein;

presenting a curved surface to receive the design, Fig. 2. is a detailplan View of the pantograph and particularly to novel mechanism for usein showing the customary parallelogram linkage;

such pantographs for compensating for the errors Fig. 3 is a detail endelevation view showing in transference resulting from differences in thethe two opposite rails; Y movement of the tracer point, traversing theFig. 4 is a View taken in a plane perpendicular plane of the pattern,and of the scribing point to the axis of the cylinder showing variousposilo which follows the curved surface of the object. tions of ascribing point in a machine not prolo It has been common heretofore touse such vided with my compensating mechanism to inpantographs formarln'ng designs on the surdicate the errors to be corrected; and

faces of cylindrical rolls, which, after treatment Fig. 5 is a viewsimilar to Fig. 4, indicating the with acid, are used to print varioustypes of fabmode of operation of my corrective mechanism. l5 rios,including rugs, and in using, for that pur- Referring to Figs. l and 2of the drawings, the 15 pose, one common type of pantograph, thecylinpantograph illustrated has a tracer point I der, usually lying onits side, is held motionless adapted to traverse a plane surfacedpattern in- While a small portion of the design is reproduced dicateddiagrammatically at 3, disposed on a suit on a limited area of theuppermost portion of the able platform 5. The tracer point I is mountedcylinder surface, after which the cylinder is roon the usual arm pivotedat 5 and Il to arms 'tated to move the next adjacent area of the cylin-I3 and I5 respectively, and supported by roller 20 der uppermost and thepantographic transference Il traversing the plate I9 adapted to bear theis continued. weight of the pantograph parallelogram. The The planesurface of the pattern results in a arms I3 and I5 are pivoted to theclosing arm 2I movement of the tracer point over the pattern enof theparallelogram. The arm I5 extends be- 25 tirely within a singlehorizontal plane. The .Vond the arm 2|, and iS adjustably lOVOled at 23scribing or marking point or points of the pantoto the framework of themachine. graph, on the other hand, rise and fall vertically A post 25 issecured to the arm 2| to depend with the arched surface of the cylinderas they downwardly therefrom, and it is secured at its follow the tracerpoint movement. As a result lower end to the horizontally dSpOSed bal2l. A 30 of these differences in movement, all lines on the companionbar 29, extending parallel to the bar plane surface of the pattern whichare parallel 2l', iS linked With the bal 21 by bands 3l and 32 to theaxis of the cylinder, and hence do not passing around pulley 33, wherebywhen the bar produce any vertical movement in the scribing 2'! is movedlongitudinally in one direction, the point, will be reproduced on thecylinder without bar 29 iS InOVed longitudinally either in the same ,35distortion, but all other lines, which do involve direction or in theODDOSi direction, als desired, varying amounts of vertical movement ofthe and depending UDOn Whe her the Pulley 33 iS scrihing point, will bedistorted in varying locked or free to rotate. Such mechanism is wellamounts depending chiefly upon the amount of known and iS employed OIeffecting Opposite di- Such Vertical movement rections of motion' ofdifferent scribing points to 40 It is the object of my invention tocorrect such lliefeverse deslgns on opposlt? ends of the distortions,and I have found that they may be The linkage connecting the bars 2.'and 29 entirely eliminated by incorporating into the y with thedifferent scribing points 'I5 engaging the pantograph, mechanism adaptedto impart to the linkage holding each scribing point a slight qmfa of.Cyhilder'm 1s 0.1115 dlagramma'tlcany 45 movement in addition to thatimparted to it by Illustrated n? Flg eicept m so far as Phe appa" thetracer point movement so that the scribng ratus of my invention 1sconcerned, but 1n general the bar 2l is connected to a rail 35 by yokes3l point moves a greater or lesser distance than norand 3g, and the bar29 is Similarly connected to a mal, depending upon the error to becorrected. mil gg by yokes 43 and 45 As indicated in Fig. 50

These and further Objects and adVentageS 0f 3, the rails 35 and 4I, whenin central position, my invention Will apnea-I frOIn 2 more detailed arespaced slightly above and at equal distances` describing thereof, takenin connection with the to opposite sides of the uppermost line of tan;accompanying drawings, in which: geiicy of the cylinder lil. The rails35 and 4| Fig. l is a perspective View showing the skelesupport arms 5Icarrying the scribing points 15 55 cross-section as and I haveillustrated in Fig. l, one arm 5i as attached to rail 35 at the lefthand end of the cylinder and another arm 5I attached to the rail il atthe opposite end of the cylinder, which is a customary arrangementv formarking designs simultaneously on opposite ends of the cylinder. Withthat arrangement the reversing mechanism at 33 would usually be madeoperative to eiect reverse markings on the two ends of the cylinder. l'twill be noted from Fig. 3 that the arms 5| carried by the rail 35 andthe arms 5I carried by the rail lli extend inwardly from oppositedirections to bring their scribing points 'i5 in alignment with eachother on the upper line of tangency of the cylinder.

With the exception oi the connections, hereinafter to be described indetail, between the scribing points 'l5 and the yokes supporting therails 35 and lil, all of the foregoing mechanism is old and well knownin the art and accordingly need not be further described. It is obviousthat as the tracer point l traverses the pattern 3, post will follow themovement of the tracer point in the same scale or in a larger or in asmaller scale, depending upon the adjustment of the various pivot pointsof the parallelograrn, and that the bars 2li and 29 will follow themovement of the post 25 moving in the same or opposite directionslongitudinally of the cylinder, depending upon the adjustment of thereversing mechanism, but, in any event, moving together in directionsaround the cylinder. The yokes supporting the rails and ii will impart asimilar movement to those rails and thence through the arms 5l will movethe scribing points l5.

I have indicated in l the usual connections between the yokes and thescribing points and the errors in transference which arose from the useoi pantographs so constructed. Whereas I have shown the connectionsthrough only one rail, it will be understood that the same principleapplies to the opposite connections. As indicated, each arm 5l, carryinga scribing point l5, is pivoted at 53 to a grooved bracket slidablymounted on the rail shaped in indicated. Each arm 5I is mounted on itsindividual bracket 55 and the slidable connection between the brackets55 and the rail 35 is for the purpose of readily adding or eliminatingone or more scribing points and for adjusting them in differentpositions lengthwise ci the rail, to position the design as desired cnthe cylinder. In prior devices of this nature, the rails have beensecured directly to the yokes, as by being bolted thereto, and with thisconstruction the pivot point 53 will move in all directions, in a singleplane, precisely the distance desired for the scribing point to moverelative to the movement of the tracer point and depending upon thescale reduction or increase for which the machine is adjusted.

To indicate the errors arising from transference to a cylindricalsurface, let us assume that the scribing point is to move only in aplane which is perpendicular to the axis of the cylinder, as indicatedin Fig. 4, for it is with such movements that the errors are greatest.Let us also assume that the maximum movement of the pivot point is fromposition 53a, on one side of the central position indicated at 53, toposition 53h on the other side. In moving between these two cxtremepositions the scribing point will move between the extreme positionsindicated at 715e and h. As stated, the pivot point 53 moves preciselythe distance desired for the scribing point 75 to move and if thedistance from 53 to 53h be measured off around the surface of thecylinder in the direction of the point i519, where the scribing pointactually came to rest, it Will be found that the point desired falls atl5b, or an appreciable distance greater than the distance actuallyinscribed.

The chief factor giving rise to this error is that in moving from thepoint 'l5 to the point 15b, the arm 5i gradually rotated fromapproximately a horizontal position to the inclined position 5th, andthis rotation caused the point l5 to traverse a distance less than wasdesired.

On the left hand side of the cylinder, the error is much larger than onthe right hand side, with the mechanism illustrated, and in this casethe error is one which causes the scribing point to traverse a distancegreater than was desired, rather than a lesser distance, as was the caseon the right hand side. the correct distance desired, be measured on thesurface of the cylinder from the point l5 toward the point 5a, it willbe found that the correct distance terminates at the point ld', adistance considerably less than that actually reached by the scribingpoint. It will be observed that in this case, as the pivot point 53 wason the same side of the cylinder as that traversed by the scribingpoint, the arm 5i rotated through a greater angle and that that angletended to increase the length transcribed as illustrated.

Referring now to Figs. 1 and 5, I will describe the mechanism I havedevised for compensating for these errors. Instead of mounting the rails315 and :il rigidly to the yokes 3l, 33, G3 and 45, according to theprior practice and as indicated in Fig. 4, I rotatably secure throughthe lowermost extensions of the yokes, the shafts 55 and 5l', whichshafts, though rotatable in the yokes, are secured against longitudinalmovement in the yokes by blocks 55 secured to the shafts 55,

and 5l, and fitting between the forked lower ends of the yokes. Therails 35 and "il are now rigidly secured to the blocks 59 thus securedto the rotatable shafts and by this arrangement the rails move with theyokes but also may rotate about the axis oi the shafts 55 and 5l.

Each shaft carries secured to it a pair of spaced arms 5! and 63,connected at their upper eX- tremities by a rod 65, riding on a curvedcam surface 5l' (Fig. 5) of a bar (iii, suitably secured to theframework of the machine. A counterweight (Fig. 5) maintains the rod 65against cam surface 6l'.

As indicated in Fig. 5, as the pivot point 53 now moves to the point 53aor 53h', the rod 55 traverses the cam surface 5l, and imparts rotativemovement to the shaft 55, which gives the desired correction tocompensate for the curvature of the surface of cylinder lil. Thus, asthe pivot point 53 moves to the point 53a', that point will be rotatedslightly about the axis ci? shaft 55 in a counterclockwise direction tocause the scribing point 'l5 to move a lesser distance than it wouldhave moved without such rotation of the pivot point, with the resultthat the s-cribing point 'i5 will now move to the desired point 65arather than to the point 25a as before. The cam surface el' is properlydesigned not only to produce the precise amount of rotation necessary toproduce the desired correction, but alsoto impart that correctiverotation in gradual increments, proper for the curvature of cylinder i0,so that the correct distance is traversed regard- If the distance 53 to53a,

less of how extensive. The carni is of course designed to give theproper corrective movement when the scribing point 'l5 moves in the bdirection.

I have described above a particular type of pantograph and a specificmanner of curing certain errors inherent in the constructionillustrated. It is obvious that the particular amount and kind of erroris immaterial, so far as my method of correcting it is concerned,because different sorts of error can be corrected by appropriatelydesigning the cam surface 61 and this surface may Vary upon a merechange in the radius of the cylinder being marked.

Under some working conditions it may be necessary to provide only anapproximate correction of the error incident to the curvilinear surfaceand in that event the cam may take the form of one or more straightedges set at the proper angles necessary for the correction desired,When using such straight edges, compensation for cylinders of differentradii may be eifected by merely changing the inclination of the straightedge cams. Furthermore, corrections for curvilinear surfaces of alltypes are within the scope of my invention and I do not wish to limitmyself to the use of correcting mechanism merely for cylindricalsurfaces.

Also some types of pantograph may not employ the pivoted arm giving riseto the error above discussed, but, in such machines an error may arisechiefly from the difference between the arc traversed by the scribingpoint and the chord subtending that arc. All such errors may beeliminated by imparting to the linkage an additional corrective movementand my invention is not to be limited to such details except asindicated in the appended claims.

I claim:

1. In a pantograph for transcribing a design from a pattern to a surfacewhich doesnot lie in a plane parallel to the face of the pattern, thecombination of a pattern-following tracer point, scribing means formarking the surface, linkage connected at one end to the said tracerpoint and at its other end to the scribing means adapted to move thescribing means over the surface upon movement of the tracer point overthe pattern and means adapted to impart movement to the said linkageindependent of the movement imparted to it by movement of the tracerpoint, to correct distortions arising from the movement of the scribingmeans in following said surface.

2. In a pantograph for-transcribing a design to a curved surface, thecombination of a patternfollowing tracer point, scribing means formarking the curved surface, follower mechanism connected to the tracerpoint and having a member movable, by said connections, in pathsgeometrically similar to the movement of the tracer point, linkageconnected at one end to the said member to move therewith in said pathsand at its other end to the scribing means to move the latter over saidcurved surface and means adapted to impart movement te the said linkageindependent of the movement imparted to it by said member to correctdistortions arising from the curvilinear movement of the scribing meansin following said surface.

3. In a pantograph for transcribing a design to a curved surface, thecombination of a pattern-following tracer point, scribing means formarking the curved surface, follower mechanism connected to the tracerpoint and having a member movable, by said connections, in pathsgeometrically similar` to the movement of the'tracer point,linkagepivotally connected at oneend to the said member to movetherewith in said paths and connected at its other end to the scribingmeans to move the latter over said curved surface, and means adapted toswing the said linkage about said pivot to impart movement to the saidlinkage independent of the movement imparted to it by said member, tocorrect distortions arising from the curvilinear movement of thescribing means in following said surface.

4. In a pantograph for transcribing a design to a curved surface, thecombination of a pattern-following tracer point, scribing means formarking the curved surface, linkage connecting the tracer point and thescribing means adapted to move the scribing meansV over the curvedsurface upon movement of the tracer point over the pattern, a cam andcam following means engaging said cam and connected to said linkage, the

said cam following means co-operating with said cam to vary the movementimparted to the scribing means by the tracer point to correctdistortions arising from the curvilinear movement of the scribing meansin following said surface.

5. In a pantograph for transcribing a design to a curved surface, thecombination of a pattern-following tracer point, scribing means formarking the curved surface, follower mechanism connected to the tracerpoint and having a member movable, by said connections, in pathsgeometrically similar to the movement of the tracer point, linkagepivotally connected at one end to the said member to move therewith insaid paths and connected at its other end to the scribing means to movethe latter over said curved surface, a stationary cam, and cam followermeans engaging said cam and connected to said linkage to be moved overthe surface of said cam by movement of the linkage, the said cam surfacebeing designed to impart movement to the said linkage independent of themovement imparted to it by the said member to correct distortionsarising from the curvilinear movement of the scribing means in followingsaid surface.

6. In a pantograph for transcribing a design to the surface ofa-cylinder, the combination of scribing means for marking the cylinder,a pattern-following tracer point connected to the scribing means to movethe latter to any point desired within an area on the surface of thecylinder extending a limited distance lengthwise of the cylinder andlimited equal distances on opposite sides of a line in the surface ofthe cylinder parallel to the axis thereof, a cam, and camfollowing meansengaging the cam and connected to the scribing means to control themovement imparted to the scribing means by the tracer point, the saidcam having a cam surface designed to correct the extent of movement ofthe scribing means in all directions not parallel to the said linewhereby to correct errors in transference incident to the curvature ofsaid cylinder.

7. In a pantograph for transcribing a design to the surface of acylinder, the combination of scribing means for marking the cylinder, apattern-following tracer point connected to the scribing means to movethe latter to any point desired within an area on the surface of thecylinder extending a limited distance lengthwise of the cylinder andlimited equal distances on opposite sides of a line in the surface ofthe cylinder parallel to the axis thereof, a cam, and cam-followingmeans engaging the cam and connected to the scribing means to controlthe movement imparted to the scribing means by the tracer point, thesaid cam having one surface portion designed to increase the extent ofmovement of the scribing means over that imparted to it by the tracerpoint when the scribng means moves on one side of the said line in anydirection not parallel thereto and another cam portion designed todecrease the extent of such movement on the other side of said linewhereby to correct errors in transference incident to the curvature ofsaid cylinder.

EDWIN W. STONE.

